Ultrafast plasma immersion strategy for rational modulation of oxygen-containing and amino groups in graphitic carbon nitride

The co-modulation of the oxygen-containing and amino groups in the polymeric semiconductor graphitic carbon nitride (g-CN) has increasingly become a common concern toward advanced catalysis, energy and biomedicine applications. The intensive understanding of the existence state of oxygen-containing and amino groups in the polymeric structure of g-CN and the controllable methods of modulating these groups is highly desirable. Herein, a rational industrially applicable plasma strategy was designed and applied for controllable modulation of oxygen-containing and amino groups in g-CN within 10 min. X-ray diffractometry, Fourier transform infrared spectrometry, and X-ray photoelectron spectroscopy results indicated that the oxygen-containing and amino groups were controllably introduced after plasma treatment. Transmission electron microscopy, atomic force microscopy and N-2 adsorption-desorption measurements verified the ultra-thin and two-dimensional in-plane mesoporous morphology of the optimized g-CN-O-NH2. As a result, the rational g-CN-O-NH2 performed well in Cr(VI) photoreduction, photocatalytic bacterial disinfection and inactivation of tumor cells. The remarkable extensively applicable photocatalytic activity can be ascribed to the fast charge carrier transfer benefiting from the enriched preferable internal edge sites and ideal joint effect of internal -NH2 and OH- groups, as confirmed by the significantly weakened PL fluorescence intensity and prolonged fluorescence lifetime of the excited states under visible light irradiation. This work provides an impressive industrially applicable strategy for the structure optimization and functional groups modulation of polymeric materials towards enhanced electronic and catalytic performances. (C) 2019 Elsevier Ltd. All rights reserved.